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Thread: 1275 Blueprints

Discuss the Austin Healey Sprite and the MG Midget. Two different but similar cars sometimes referred to collectively as the Spridget.

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    1275 Blueprints

    Greetings all,
    I'm looking for the engine blueprints for the 1275 MG Midget engine, anybody know where I can find them?
    Thank you!

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    Jedi Warrior BlueMax's Avatar
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    Re: 1275 Blueprints

    This will give you all the specs you'll need.

    https://www.bentleypublishers.com/br...1967-1974.html

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    Re: 1275 Blueprints

    Thanks Blue Max but I already have that manual. What I am looking for are the actual specification drawings that show all the dimensions, hole & thread specs, cylinder center to center dimnsions, etc.

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    Jedi Warrior BlueMax's Avatar
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    Re: 1275 Blueprints

    If your engine is intact you want need engineered drawings. Just measure what you have. I trash all my bolts anyway and go back with grade 8 or ARP for the high stress components. Why do you need cylinder center to center dimnsions?

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    Re: 1275 Blueprints

    That was just an example, but C to C dimensions would allow me to adjust the cylinder bores at re-boring time to put them where they should be providing cylinder wall thickness will allow it. Also for things like camshaft to crankshaft alignment, relationships between parallel but non co-planer surfaces, etc. I'm looking for all the details as they were originally intended for design purposes for other accessories and options. I'm a bid of a mad tinkerer!

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    Great Pumpkin JPSmit's Avatar
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    Re: 1275 Blueprints

    Quote Originally Posted by Stan Kowznofski View Post
    That was just an example, but C to C dimensions would allow me to adjust the cylinder bores at re-boring time to put them where they should be providing cylinder wall thickness will allow it. Also for things like camshaft to crankshaft alignment, relationships between parallel but non co-planer surfaces, etc. I'm looking for all the details as they were originally intended for design purposes for other accessories and options. I'm a bid of a mad tinkerer!

    That's a whole new level of crazy! well done sir. I am not aware that what you seek exists though. (at least not easily) perhaps an engine builder? or one of the bigger clubs.

    Hap Waldrop is just getting re-acquainted with the forum - her builds race engines - https://www.acmespeedshop.com/ - he might know.
    John-Peter Smit
    1976 MG Midget
    1969 Vauxhall Viva GT
    1958 Fiat Multipla (Barn art)

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    Re: 1275 Blueprints

    I once built a Briggs & Stratton racing go kart engine where I offset and angle bored the cylinder to improve the connecting rod angle then angle milled the engine deck to 90 degrees to the cylinder to help unshroud the valves (remember, it's a flathead) and disguise the angle bore and then machined the engine bottom parallel to the deck so the tech inspectors wouldn't notice. The only way to find it would be to measure the cylinder centerline to the crankshaft centerline & they didn't have the tooling sophisticated enough to determine the offset. Made incredile horsepower, relatively speaking of course!

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    Jedi Warrior BlueMax's Avatar
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    Re: 1275 Blueprints

    A and B type BMC engines have inconsistency with core slippage. You would be better off in machining adapters after you ultrasound the block and use the main bearing centerline. You can then probe all your centers with a C & C probe to determine what you have to work with.

    https://www.youtube.com/watch?v=7avTX3BNmuA


    There's several 1275 blocks to choose from one is the most coveted , if you don't have this book you'll find a HUGE amount of useful information. Tuning The A Series Engine by David Vizard third edition.
    Last edited by BlueMax; 02-23-2019 at 10:01 AM.

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